this shows a picture of the op-amps... but im sure the guy replaced the wrong op-amps.. he swapped the single channel with the duel channel ones. the labeled duel channel ones should be a jrc (number i cant remember) and the single channel 2 should be lme49710na

Purple Angel . The metal versions are generally of a higher spec. Used by military/government .Whether they still use them I dont know But very high quality electronics in the past decades had them in them. Yes original ICs were metal but they were dear to buy then. My digital IC book lists well known US companies who manufactured them -So on a like for like basis the metal were better. That didnt help when it came to soldering them into a PCB by hand.

Oh. I am sending my ATH Pro 700 MKII for his Xonar STX with the replaced op amps. I barely used the headphones and decided they weren't my style as I am too in love with my Q701. Plus I bought them expecting more bass when I should have realized being a monitor that they would be cold and direct. I was dumb when I bought them. haha

It's Rikuo btw who is sending them. We usually chat on another forum than this one but are aspiring audiophiles. He said he replaced the op amp to balance out his DT990s. I will see how they do and I might keep them or swap them out once I learn more about op amps.